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On foot through Chernobyl with Medical Physicists

It’s a two hour drive to Chernobyl from the Ukrainian capital, Kiev, through mile after mile of flat, pine-covered countryside. There’s no indication that we’re approaching the site of the worst nuclear power disaster in history; even when we reach the edge of the Exclusion Zone, 30km from the ruined reactor, there’s nothing visible beyond the checkpoint except the long, flat road between the trees.

Soldiers check each passport carefully and wave us through. As our minibus crosses into the Zone, our guide reminds us of the rules: no eating, no touching, no souvenirs.

If the destination is unconventional, our group is equally eccentric. We’re a group of nine: eight British physicists, for whom the prospect of visiting a nuclear disaster zone is not bizarre but compelling, and one game partner. Our visit was organised by Henry Lawrence and the UK Monte Carlo Radiation Transport User Group; most of us work in hospital radiology and radiotherapy departments, and we’re used to dealing with low level radiation incidents, from faulty x-ray equipment to spilt radioactive drugs. Chernobyl, however, is on another scale.

The first thing that strikes you is the trees: all we can see above three decades of forest are the tops of apartment blocks and the uppermost yellow carriages of a Ferris wheel. We park on the empty road and step into thick undergrowth, passing in single file down tracks that were once highways.

It’s a changeable day, sunny with sudden showers. Yellow butterflies dance around us, and the air is heavy with the smell of pine trees in the heat. Away from the derelict buildings and rusting industrial junk, this is a strangely pleasant place for a walk.

Our guide sweeps his Geiger counter slowly near the ground; the clicking accelerates as it passes over “hotspots”, otherwise indistinguishable from surrounding earth. I think we’re less impressed than he hoped – many of us do something similar at work, detecting small radioactive spillages.

We peer through dirty windowpanes. The floorboards have collapsed in splinters and books spill out onto the damp earth, Cyrillic lettering still clear. They look like science schoolbooks, rejected by looters. We step around them carefully – it feels wrong to tread on books. A brightly coloured calendar still hangs on one wall, with drummers marching beneath the date – 1986.

The Accident and Aftermath

1986: in the early hours of the 26 April, Chernobyl Nuclear Power Plant’s Reactor 4 exploded during a safety test. The fire raged for days, releasing clouds of radioactive material into the atmosphere. This fell largely on surrounding countryside and towns, with some carried further across Ukraine, Belarus and Russia, and beyond.

One of the most significant contaminants was iodine-131, a radionuclide which is taken up by the human thyroid. This process is used in hospitals under carefully controlled conditions to treat thyroid conditions including cancer, usually with excellent results. Its half-life is eight days; 31 years on, we have nothing to worry about, but uncontrolled ingestion soon after the accident would lead to a huge increase in thyroid cancer across Ukraine, Belarus and Russia, particularly in children.

Also affected were the plant workers and “liquidators” brought in to battle the fire and contain the spread of contamination; many received very high radiation doses, and 28 died of radiation sickness within three months. The longer term impact, however, is harder to assess, given the hundreds of thousands of evacuees and liquidators, and the delay of years or decades before radiation-induced cancers can occur. However, the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) has concluded that, with the notable exception of thyroid cancer, “there is no clearly demonstrated increase in the incidence of solid cancers or leukaemia due to radiation in the exposed populations”. The enormous psychological stress of evacuation, however, is not in doubt.What about the risk to visitors? Our radiation doses were surprisingly small. Our guide’s personal monitor recorded 10µSv over our two day visit, which might translate, given generally used estimates, to a cancer risk of very roughly 1 in 2 million. I have some scepticism about this measurement – background radiation in the UK is about 7µSv per day, so I apparently received a lower dose in Chernobyl than I would have got sitting on my sofa at home. There’s also the risk of contamination, for which we were checked every few hours. However, the biggest radiation dose from this trip probably came from my flight to Kiev.

Pripyat and the Nuclear Power Plant

We tramp on through the overgrown outskirts of Pripyat, the Soviet city purpose-built for plant workers and their families. This was once a good place to live; the streets were spacious, with a striking range of amenities: a Cultural Palace, swimming pools, gyms and a supermarket where dusty signs still hang above the aisles. A shop we pass is full of cracked televisions, huge and box-like; the one next door houses dozens of upright pianos.

We are visiting not just another time, but a country that no longer exists: the Ukrainian Soviet Socialist Republic, gone since 1991. Trees grow so dense that sixteen-story apartment blocks are barely visible until we get close, their empty windows gaping black. Broken glass crunches under our feet. We are surrounded by the effects of abandonment, but without our Geiger counter clicking in excited bursts it would be impossible to guess why these people left so suddenly.

Outside Pripyat stands what’s left of Chernobyl Nuclear Power Plant: an unfinished cooling tower, industrial buildings and, most prominently, the smooth white semicylinder of the new sarcophagus concealing the remains of Reactor 4.

The dose rate here, about 100 yards from the sarcophagus at the only permitted photo spot, is 1µSv/hr – remarkably low considering what’s hidden underneath. For comparison, in hospital nuclear medicine departments, staff might come into (brief) contact with levels at least ten times higher, from patients having radionuclide therapy.

Duga-1 Radar Station

Back in the minibus, we drive on in search of the most mysterious place within the Zone: the abandoned Soviet radar station, Duga-1. Part of an early-warning system for anti-ballistic missiles, this colossal array of caged radar transmitters is vast almost beyond comprehension, stretching hundreds of metres up and as far as the eye can see. Despite this, it’s almost invisible until you are right upon it, carefully hidden from the road by forest.

The station and attached settlement went unmarked on maps, passed off as a children’s holiday camp complete with fake, brightly-muralled bus stop. The school is real, though; toys and gas masks litter the ground beneath posters of great classical composers still hanging on the walls: Tchaikovsky, Beethoven, Rimsky-Korsakov.

Thirty-one years ago Duga-1 would have been closely guarded, with soldiers on watch while in the school their children learned classical music. Now, no one protests as British physicists with cameras walk past.

Our minibus is waiting beyond the checkpoint, but first we are checked one last time for contamination, stepping in turn between detectors. All clear: the turnstile clicks open and we’re through. With a last look back, we climb into the minibus, shaking the dust of Chernobyl from our feet.

The Future

What does the future hold for Chernobyl? As the Zone enters its fourth decade, the need for a long term plan is ever more pressing. Decontamination work continues, but the buildings are now so dilapidated that they present a real hazard, and a decision must be made soon on whether they should be pulled down. That would be a complicated process, potentially releasing large quantities of radioactive dust.

These same buildings also provide an unlikely source of income for the Ukrainian government. Since its opening in 2011, thousands of visitors have entered the Exclusion Zone annually, drawn by professional curiosity, historical interest or the lure of the unusual. Visitors must be part of accredited tours and entry is strictly controlled. Tourists usually visit Kiev too, bringing much needed income to an industry badly hit by the fighting in eastern Ukraine.

The Ukrainian government faces a quandary: entering abandoned buildings is officially forbidden, but it is an open secret that visitors want to do more than peer through broken windows. As buildings crumble, it’s only a matter of time before someone is injured by collapsing walls or falls through floorboards. On the other hand, will tourists still come if all they can see are pine trees?

There are possibilities, however, for Chernobyl’s future. One is to make some of the more impressive structures safe for authorised visits while others are demolished. Over the border, the Belarusian share of the Exclusion Zone is now a huge wildlife reserve, the Polesie State Radioecological Reserve. Research into environmental effects of radiation continues, and there is even talk of inclusion on the UNESCO World Heritage List. Others have mooted using the Zone as a huge solar farm: a fitting future for energy production’s most notorious disaster site.

Katharine Thomson is a member of the BIR Radiation Safety Special Interest Group (SIG) and also represents the BIR at the Society of Radiological Protection’s International Committee, which connects the UK radiation protection community with the worldwide scene. She is Principal Physicist at Derriford Hospital, Plymouth.